Himadri Soni | BHAVNAGAR UNIVERSITY (original) (raw)
Papers by Himadri Soni
Applied Physics Letters, 2016
Advanced Materials Research, 2013
Using first principles density functional theoretical calculations within the generalized gradien... more Using first principles density functional theoretical calculations within the generalized gradient approximation (GGA), the present paper reports thermal properties such as constant volume lattice specific heat, Gibb's free energy, internal energy, and entropy of Yb-pnictides such as YbN, YbP and YbAs in its rocksalt phase. The variation of lattice specific heat with temperature obeys the classical Dulong-Petit's law at high temperature while at low temperature it obeys Debye T 3 law. The internal energy, entropy and free energy show a gradual variation with temperature. The specific heat at constant volume at lower temperature increases as going from N to P to As.
![Research paper thumbnail of Electronic and Phonon Properties of BaF[sub 2] Studied By Density Functional Methods](https://attachments.academia-assets.com/50614423/thumbnails/1.jpg)
](Ground state properties of face centered cubic fluorite BaF 2 is investigated using first princip... more Ground state properties of face centered cubic fluorite BaF 2 is investigated using first principle method. The calculated lattice constants, bulk modulus are reported and compared with available experimental and theoretical data. The band structure and electronic density of states conforms that the BaF 2 is ionic. The phonon dispersion and phonon density of states are also presented and analyzed.
Solid State Communications, 2014
The present paper reports the calculated vibrational and elastic properties of some two dimension... more The present paper reports the calculated vibrational and elastic properties of some two dimensional carbon allotropes such as graphene, α-, βand γ-graphynes using first principles density functional theory. The phonon modes of graphynes show quite distinct behavior than graphene and have real frequency throughout the Brillouin zone thus indicating dynamically stable structures. The out of plane, ZA mode is more dispersive in the case of graphynes. We have discussed the implications of phonon modes to the thermal conductance in graphynes and graphene. We have also calculated the elastic constants for graphene and graphynes. Calculated elastic constants of graphynes show more anisotropic conformer nature than graphene.
Materials Chemistry and Physics, 2014
The electronic band structure and density of states-calculations show metallic nature. Rocksalt s... more The electronic band structure and density of states-calculations show metallic nature. Rocksalt structure of TMN indicating dynamical stability. The calculated superconducting transition temperature agrees well with the experimental data. These compounds behave as a conventional phonon-mediated superconductor. Using quasi-harmonic approximation, thermodynamical properties are investigated.
A comprehensive first principle study of thermodynamic properties of MgN is reported within the d... more A comprehensive first principle study of thermodynamic properties of MgN is reported within the density functional theory scheme. The ground state properties such as lattice constant, Bulk modulus etc. of MgN in rock-salt (RS) phase have been determined. The thermodynamical properties have been analyzed in the light of phonon density of states of MgN and its constituent atoms. The variation of lattice-specific heat with temperature obeys the classical Dulong-Petit's law at high temperature while at low temperature it obeys Debye T 3 law. The phonon spectrum shows the presence of all positive phonons and zero phonon density of states at zero energy confirming a dynamically stabilized structure of MgN in RS phase.
Journal of Applied Physics, 2014
In the frame work of density functional theory, the biaxial strain induced phonon dispersion curv... more In the frame work of density functional theory, the biaxial strain induced phonon dispersion curves of monolayer boron pnictides (BX, X ¼ N, P, As, and Sb) have been investigated. The electron-ion interactions have been modelled using ultrasoft pseudopotentials while exchange-correlation energies have been approximated by the method of local density approximation in the parameterization of Perdew-Zunger. The longitudinal and transverse acoustic phonon modes of boron pnictide sheets show linear dependency on wave vectork while out of plane mode varies as k 2 . The in-plane longitudinal and out of plane transverse optical modes in boron nitride displaying significant dispersion similar to graphene. We have analyzed the biaxial strain dependent behaviour of out of plane acoustic phonon mode which is linked to ripple for four BX sheets using a model equation with shell elasticity theory. The strain induces the hardening of this mode with tendency to become more linear with increase in strain percentage. The strain induced hardening of out of plane acoustic phonon mode indicates the absence of rippling in these compounds. Our band structure calculations for both unstrained and strained 2D h-BX are consistent with previous calculations. V C 2014 AIP Publishing LLC. [http://dx.
We present results of first principles total energy calculations of the structure, electronic and... more We present results of first principles total energy calculations of the structure, electronic and lattice dynamics for beryllium semiboride and its three ternary alloys using generalized gradient and local density approximations under the framework of density functional theory. The generalized gradient approximation is used for all compounds except MgBeB using the Perdew–Burke–Ernzehorf exchange correlation functional while local density approximations use the Perdew–Zunger ultrasoft exchange correlation functional. The calculated ground state structural parameters are in good agreement with those of experimental and previous theoretical studies. The electronic band structure calculations show that Be2B may transform to a semiconductor after Al substitution. A linear response approach to density functional theory is used to calculate phonon dispersion curves and vibrational density of states. The phonon dispersion curves of Be2B and AlBeB are positive indicating a dynamical stablility of the structure for these compounds. The phonon dispersion curves of NaBeB and MgBeB show the imaginary phonons throughout the Brillouin zone, which confirms dynamical instability as indicated in band structures for these alloys. We also present the partial phonon density of states for different species of Be2B and AlBeB to bring out the details of the participation of different atoms in the total phonon density of state, particularly the role played by Al atom. The first time calculated phonon properties are clearly able to bring out the significant effect of isoelectronic substitution in Be2B.
The structural, electronic, vibrational and thermodynamical properties of transition metal carbid... more The structural, electronic, vibrational and thermodynamical properties of transition metal carbides RuC, RhC, PdC and AgC are investigated using the plane-wave pseudopotentials method within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT). There is a good agreement between present theoretical and available experimental theoretical data in the case of ground state properties such as lattice parameter and bulk modulus. The electronic band structure of these compounds show that all compounds except RuC in zinc blende phase are metallic in nature. RuC in zinc blende phase is semiconducting in nature with an indirect band gap. The phonon properties of RhC, PdC and AgC are investigated for the first time. The phonon frequencies in the phonon dispersion curves are positive throughout the Brillouin zone for zinc blende RuC and AgC and rocksalt RhC and PdC indicating dynamical stability for these compounds in the said phases. Temperature variation of thermodynamical properties for noble metal carbides are calculated and discussed.
A density functional theory study of epitaxial graphene on the (3×3)-reconstructed C-face of SiC ... more A density functional theory study of epitaxial graphene on the (3×3)-reconstructed C-face of SiC Appl. Phys. Lett. 102, 093101 (2013) Magnetic and electronic properties of Fe3O4/graphene heterostructures: First principles perspective J. Appl. Phys. 113, 083711 (2013) Inverse relationship between carrier mobility and bandgap in graphene J. Chem. Phys. 138, 084701 (2013) Directional quantum transport in graphyne p-n junction
The Yb-pnictides have drawn considerable interest in the field of solid state and material scienc... more The Yb-pnictides have drawn considerable interest in the field of solid state and material science due to it's diverge applications in the properties like electronic, magnetic, optical and phonon. These compounds have got keen interest due to its partially filled 4f bands. In the frame work of density functional theory (DFT), we determine structural, electronic, lattice dynamical and elastic properties of Yb-pnictides (YbX, X= N, P, As) in rocksalt (RS) phase using first-principles density functional theory (DFT) simulations based with a generalized gradient approximation (GGA) of the exchange correlation energy implemented in ABINIT package.
Using first principles density functional theoretical calculations, the present paper reports a s... more Using first principles density functional theoretical calculations, the present paper reports a systematic nonspin and spin polarized total energy calculations of the lattice dynamical and a number of other properties such as band structure, structural and magnetic moment of two mononitrides FeN and CoN. The phonon dispersion curves and phonon density of states in the case of FeN and CoN have been determined for the first time and discussed. The structural and dynamical calculations suggest that the zinc blende structure is preferred at ambient pressure for both compounds. The rocksalt FeN has a nonzero magnetic moment while for FeN in zinc blende phase, it is either zero or very small. The zinc blende phase for both compounds is nonmagnetic. The spin calculation offers an intensive opportunity to understand the role of spin on the phonon properties of two mononitrides. Majority of the modes are sensitive to the effect of spin due to the modification of lattice constant. In this work we reveal that spin modifies the interionic interactions and local structure and leads to a flexible lattice which can be used for the functional materials design.
Applied Physics Letters, 2016
Advanced Materials Research, 2013
Using first principles density functional theoretical calculations within the generalized gradien... more Using first principles density functional theoretical calculations within the generalized gradient approximation (GGA), the present paper reports thermal properties such as constant volume lattice specific heat, Gibb's free energy, internal energy, and entropy of Yb-pnictides such as YbN, YbP and YbAs in its rocksalt phase. The variation of lattice specific heat with temperature obeys the classical Dulong-Petit's law at high temperature while at low temperature it obeys Debye T 3 law. The internal energy, entropy and free energy show a gradual variation with temperature. The specific heat at constant volume at lower temperature increases as going from N to P to As.
Ground state properties of face centered cubic fluorite BaF 2 is investigated using first princip... more Ground state properties of face centered cubic fluorite BaF 2 is investigated using first principle method. The calculated lattice constants, bulk modulus are reported and compared with available experimental and theoretical data. The band structure and electronic density of states conforms that the BaF 2 is ionic. The phonon dispersion and phonon density of states are also presented and analyzed.
Solid State Communications, 2014
The present paper reports the calculated vibrational and elastic properties of some two dimension... more The present paper reports the calculated vibrational and elastic properties of some two dimensional carbon allotropes such as graphene, α-, βand γ-graphynes using first principles density functional theory. The phonon modes of graphynes show quite distinct behavior than graphene and have real frequency throughout the Brillouin zone thus indicating dynamically stable structures. The out of plane, ZA mode is more dispersive in the case of graphynes. We have discussed the implications of phonon modes to the thermal conductance in graphynes and graphene. We have also calculated the elastic constants for graphene and graphynes. Calculated elastic constants of graphynes show more anisotropic conformer nature than graphene.
Materials Chemistry and Physics, 2014
The electronic band structure and density of states-calculations show metallic nature. Rocksalt s... more The electronic band structure and density of states-calculations show metallic nature. Rocksalt structure of TMN indicating dynamical stability. The calculated superconducting transition temperature agrees well with the experimental data. These compounds behave as a conventional phonon-mediated superconductor. Using quasi-harmonic approximation, thermodynamical properties are investigated.
A comprehensive first principle study of thermodynamic properties of MgN is reported within the d... more A comprehensive first principle study of thermodynamic properties of MgN is reported within the density functional theory scheme. The ground state properties such as lattice constant, Bulk modulus etc. of MgN in rock-salt (RS) phase have been determined. The thermodynamical properties have been analyzed in the light of phonon density of states of MgN and its constituent atoms. The variation of lattice-specific heat with temperature obeys the classical Dulong-Petit's law at high temperature while at low temperature it obeys Debye T 3 law. The phonon spectrum shows the presence of all positive phonons and zero phonon density of states at zero energy confirming a dynamically stabilized structure of MgN in RS phase.
Journal of Applied Physics, 2014
In the frame work of density functional theory, the biaxial strain induced phonon dispersion curv... more In the frame work of density functional theory, the biaxial strain induced phonon dispersion curves of monolayer boron pnictides (BX, X ¼ N, P, As, and Sb) have been investigated. The electron-ion interactions have been modelled using ultrasoft pseudopotentials while exchange-correlation energies have been approximated by the method of local density approximation in the parameterization of Perdew-Zunger. The longitudinal and transverse acoustic phonon modes of boron pnictide sheets show linear dependency on wave vectork while out of plane mode varies as k 2 . The in-plane longitudinal and out of plane transverse optical modes in boron nitride displaying significant dispersion similar to graphene. We have analyzed the biaxial strain dependent behaviour of out of plane acoustic phonon mode which is linked to ripple for four BX sheets using a model equation with shell elasticity theory. The strain induces the hardening of this mode with tendency to become more linear with increase in strain percentage. The strain induced hardening of out of plane acoustic phonon mode indicates the absence of rippling in these compounds. Our band structure calculations for both unstrained and strained 2D h-BX are consistent with previous calculations. V C 2014 AIP Publishing LLC. [http://dx.
We present results of first principles total energy calculations of the structure, electronic and... more We present results of first principles total energy calculations of the structure, electronic and lattice dynamics for beryllium semiboride and its three ternary alloys using generalized gradient and local density approximations under the framework of density functional theory. The generalized gradient approximation is used for all compounds except MgBeB using the Perdew–Burke–Ernzehorf exchange correlation functional while local density approximations use the Perdew–Zunger ultrasoft exchange correlation functional. The calculated ground state structural parameters are in good agreement with those of experimental and previous theoretical studies. The electronic band structure calculations show that Be2B may transform to a semiconductor after Al substitution. A linear response approach to density functional theory is used to calculate phonon dispersion curves and vibrational density of states. The phonon dispersion curves of Be2B and AlBeB are positive indicating a dynamical stablility of the structure for these compounds. The phonon dispersion curves of NaBeB and MgBeB show the imaginary phonons throughout the Brillouin zone, which confirms dynamical instability as indicated in band structures for these alloys. We also present the partial phonon density of states for different species of Be2B and AlBeB to bring out the details of the participation of different atoms in the total phonon density of state, particularly the role played by Al atom. The first time calculated phonon properties are clearly able to bring out the significant effect of isoelectronic substitution in Be2B.
The structural, electronic, vibrational and thermodynamical properties of transition metal carbid... more The structural, electronic, vibrational and thermodynamical properties of transition metal carbides RuC, RhC, PdC and AgC are investigated using the plane-wave pseudopotentials method within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT). There is a good agreement between present theoretical and available experimental theoretical data in the case of ground state properties such as lattice parameter and bulk modulus. The electronic band structure of these compounds show that all compounds except RuC in zinc blende phase are metallic in nature. RuC in zinc blende phase is semiconducting in nature with an indirect band gap. The phonon properties of RhC, PdC and AgC are investigated for the first time. The phonon frequencies in the phonon dispersion curves are positive throughout the Brillouin zone for zinc blende RuC and AgC and rocksalt RhC and PdC indicating dynamical stability for these compounds in the said phases. Temperature variation of thermodynamical properties for noble metal carbides are calculated and discussed.
A density functional theory study of epitaxial graphene on the (3×3)-reconstructed C-face of SiC ... more A density functional theory study of epitaxial graphene on the (3×3)-reconstructed C-face of SiC Appl. Phys. Lett. 102, 093101 (2013) Magnetic and electronic properties of Fe3O4/graphene heterostructures: First principles perspective J. Appl. Phys. 113, 083711 (2013) Inverse relationship between carrier mobility and bandgap in graphene J. Chem. Phys. 138, 084701 (2013) Directional quantum transport in graphyne p-n junction
The Yb-pnictides have drawn considerable interest in the field of solid state and material scienc... more The Yb-pnictides have drawn considerable interest in the field of solid state and material science due to it's diverge applications in the properties like electronic, magnetic, optical and phonon. These compounds have got keen interest due to its partially filled 4f bands. In the frame work of density functional theory (DFT), we determine structural, electronic, lattice dynamical and elastic properties of Yb-pnictides (YbX, X= N, P, As) in rocksalt (RS) phase using first-principles density functional theory (DFT) simulations based with a generalized gradient approximation (GGA) of the exchange correlation energy implemented in ABINIT package.
Using first principles density functional theoretical calculations, the present paper reports a s... more Using first principles density functional theoretical calculations, the present paper reports a systematic nonspin and spin polarized total energy calculations of the lattice dynamical and a number of other properties such as band structure, structural and magnetic moment of two mononitrides FeN and CoN. The phonon dispersion curves and phonon density of states in the case of FeN and CoN have been determined for the first time and discussed. The structural and dynamical calculations suggest that the zinc blende structure is preferred at ambient pressure for both compounds. The rocksalt FeN has a nonzero magnetic moment while for FeN in zinc blende phase, it is either zero or very small. The zinc blende phase for both compounds is nonmagnetic. The spin calculation offers an intensive opportunity to understand the role of spin on the phonon properties of two mononitrides. Majority of the modes are sensitive to the effect of spin due to the modification of lattice constant. In this work we reveal that spin modifies the interionic interactions and local structure and leads to a flexible lattice which can be used for the functional materials design.